RE: ICMP/SYN Flood

["Whiteside, Larry [contractor]" <BAE14 () SPHQ SSP NAVY MIL>]

Everything you are seeing should be blocked at the router. The fact that they aren't tell me a lot more is not either. 
Scary! Anyway, go to NSA's website and have them download their router config guide. It is what I use and is GREAT. It 
will give them all the things needed to lock down their router. It is very simple to follow along and they give you a 
lot of commands. If they cannot use this then God help you all!

http://www.nsa.gov/snac/cisco/download.htm

L
***************************
Larry Whiteside Jr.
Sr. Security Engineer

-----Original Message-----
From: Muhammad Naseer Bhatti [mailto:mail-lists () digitallinx com]
Sent: Wednesday, May 21, 2003 10:47 PM
To: incidents () securityfocus com
Subject: ICMP/SYN Flood


Hi list ..

I am experiencing a bad DDoS attack toward one of my server. The attack is
pointed to only 1 IP on which a governmental site is hosted. Seems some
folks don't like the site to stay up. As far as the Server (Linux) security
is concerned, I am able to make that up serving all requests without any
hesitation. My network with which I am connected to is poorly configured and
allowing the DDoS attack to pass thru their routers. I am getting two kind
of attacks here:

- ICMP Flood
        Simple ICMP flood from various spoofed hosts. This I know can be
blocked on the router for the particular IP. Unfortunately the network guys
are still not able to do that.

- SYN Flood
        Interesting thing. Loots of SYN requests from these kind of
network/broadcasts towards port 80 only.

37.72.0.0
128.89.0.0
173.66.0.0
37.155.0.0
177.225.0.0
37.94.0.0
36.162.0.0
117.77.0.0
151.162.0.0
36.216.0.0
134.248.0.0
175.129.0.0

And the list goes oon .. The question I want to ask here, is the
network/router poorly configured at my NOC which is allowing
broadcasts/networks to pass through it? If so, how can I assist them to fix
it? I am not a Cisco guru, so might need someone to give me some hints so
that I can pass that to the poor NOC techs.

Any help would be appreciated.


Thanks,

Muhammad Naseer

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